B737 Revision To Gear Nonnormal Cklist

[LEM]

In the last revision we received (737 classic), a new note is introduced in the GEAR LEVER WILL NOT MOVE UP AFTER TAKEOFF, regarding the failure of the ground spoiler bypass valve to close as a possibility for the gear lever not being able to be placed in the up position.

I must admit I'm not even confused, I'm lost! :O

[Popolama]

Failure of GRD spoiler bypass valve to close=failure of Air/GRD sensor ....that's what it sounds to me like....

other thoughts?

[LEM]

That would be the consequence of the failure of the air ground sensor, but this ground spoiler bypass valve seems to be the cause of the jam... :confused:

[7dirty7]

The groundspoiler bypassvalve is mechanical linked to a sensor on RH main LDG. It could very vell be, the same sensor that gives input to Air/Ground system.
So if this sensor is jammed by the (faulty) open valve, LDG Lever Lock Out solenoid will not open, due to A/G system logic, and gear lever cannot move up.

I could be wrong, but it seems like logic to me.

BTW: My QRH rev. is dated June 08, 2001. Says nothing about the new note :confused:

[CaptainSandL]

For those that have not got the new amendment (3 Dec 2004), the new procedure starts as follows:

“Condition: The landing gear lever cannot be placed to the UP position in the normal manner due to one or more of the following:

• Failure of the landing gear lever lock solenoid
• Failure of the air/ground system
• Failure of the ground spoiler bypass valve to close”

Of which the last failure is the new addition to the procedure.

The checklist then goes on to diagnose which of the failures you have and gives you the next steps, but there is no diagnosis of the new last failure or any checks for that specific failure.

MY GUESS is that someone has pointed out to Boeing that there is this third failure that can cause the condition so they have had to include it for the sake of completeness. I would also imagine (hope) that it will be operationally identical to one of the first two failures and will therefore be covered by the existing drills. To be practical, the take-off config warning horn can only either sound or remain silent after the flaps are fully retracted, which directs you either to failure 1 or 2.

Just as an aside, in case anybody has not grasped the significance of the caution “Do not operate the speedbrakes in flight” This is because if it is an air/ground problem the aircraft could think it is still on the ground and using speedbrake will deploy both flight and ground spoilers! Whilst this will silence those who say how ineffective the 737 speedbrakes are, it will also probably shake the aircraft to bits. Another reason to give yourself plenty of time in a non-normal situation.

S & L

[shlittlenellie]

Further to this, if both air and ground spoilers are deployed, the "shaking to bits" may cause the ground spoiler bypass valve to close - leaving the ground spoilers deployed.